Cable size

[Bessy765]

What size cable for linking 3 x170 watt panels together then on to the Smart Solar MPPT 100/30 regulator from there to 2 x 100 lithium. Solar to regulator 3. 5 mtr. Regulator to batteries 1 mtr.

 

[Stealaway]

The maximum size cables will fit into the controller. Probably 4mm. Possibly 6mm

 

[I2C]

I use this site: https://www.bluesea.com/resources/1437 - there are other sites that various people on here use.

 

[Bessy765]

If the batteries are at 50% DOD (2 100 amp lithium) Midsummer midday what is the theoretical max amps from three 170 watt panels.

 

[Lenny HB]

If the batteries are at 50% DOD (2 100 amp lithium) Midsummer midday what is the theoretical max amps from three 170 watt panels.

Approx 36 amps but you won't see that very often.

As for cable size 6mm sq from the panels to controller then 10mm sq to the battery.

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[Rusticrogers]

You are the dogs at this solar stuff for sure!

 

[two]

How do you fit 6mm cable into MC4 connectors?

 

[Sheddy]

Buy them already crimped on to the 6mm cable, adjust the length to suit the location of the solar controller.

 

[Lenny HB]

How do you fit 6mm cable into MC4 connectors?

Slowly.
Actually they do fit but cheaper and easier to buy a male to female MC4 cable twice the length you need and cut it in half.

 

[two]

I think I'd just double-up on the cabling.

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[Raul]

If the 3 panels go in parallel, I would fuse them individually with 8-10a fuse each. From panel to fuse even 4mm will do. Then, from fuse combiner to the controller 6mm cable. From controller to battery min 10mm cable. The ends of the stranded cable needs a end ferrule crimp to go into controller.

 

[Raul]

The maximum size cables will fit into the controller. Probably 4mm. Possibly 6mm

The victron 100/30 terminals can take 16mm cable, you need to crimp a end ferrule to go I to the connector.

 

[Ivory55]

The victron 100/30 terminals can take 16mm cable, you need to crimp a end ferrule to go I to the connector.

How many panels would that be, that’s like car battery leads ?

 

[Lenny HB]

Approx 36 amps but you won't see that very often.

As for cable size 6mm sq from the panels to controller then 10mm sq to the battery.

Edit:
Didn't read the OP correctly with only 1 m between regulator & battery, 6 mm sq will be OK.

 

[Raul]

How many panels would that be, that’s like car battery leads ?

Nothing to do with panels count, it’s amps and volts over distance. The 100/30 has the same connector block as the 100/50. I have 16mm2 on mine (100/50) from controller to battery. If you have a 0,1v drop from controller to battery, then your controller settings are in vain as the battery will always revive the set voltage minus the voltage drop. From controller to battery should be no voltage drop, so it can receive the full voltage. That’s why the manufacturers spec the block connector size big enough.

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[Stealaway]

Have you measured the volts drop compared to a 6 mm cable? How long are your tails?

 

[cmcardle75]

What size cable for linking 3 x170 watt panels together then on to the Smart Solar MPPT 100/30 regulator from there to 2 x 100 lithium. Solar to regulator 3. 5 mtr. Regulator to batteries 1 mtr.

You haven't mentioned if you'll be using parallel or serial? I'd suggest serial, as you are nominally well over the 30A limit and will need very thick cables. I believe the Victron can cope with overcurrent on the output by not drawing anything over its rating and you'd only get the maximum under basically mid summer Mediterranean conditions anyway.

Parallel provides better performance in shade (particularly with cheap polycrystalline panels with insufficient bypass diodes). Serial provides better off-season performance as it can maintain sufficient voltage to charge slowly even under low light when a parallel array has long since given up the ghost. It also has smaller cable sizes for the same efficiency.